
function _classCallCheck(sub, constr) {
  if(!(sub instanceof constr)) {
    throw new Error('cannot with new')
  }
}

let Animal = function () {
  function Animal(type) {
    _classCallCheck(this, Animal)
    this.type = type
  }
  // Object.defineProperty
  _creatClass(Animal, [{

  }]) 
  return Animal
}()
// Animal() 报错
new Animal()

// 任务11 3.es6 未完成 5.es5-class.js